Tube couplings

ABSTRACT

A tube coupling includes a coupling body having a throughway open at one end to receive an end portion of a tube, an annular step in the throughway facing the open end to provide an end stop for a tube end, and an end cap engaging the coupling body for axial movement between forward and retracted positions on the body. The end cap has an opening for the end portion of the tube to extend therethrough and a tube locking collet in the cap to permit entry of a tube into the cap and to resist withdrawal. An annular seal is located in the coupling body adjacent the annular step, the seal having an inner annular portion with which the tube end is engageable and an outer annular portion, and a sleeve between the locking device and seal to compress the outer annular portion of the seal axially.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to United KingdomApplication No. 0126798.8, filed Nov. 7, 2001 which is incorporatedherein by specific reference.

BACKGROUND OF THE INVENTION

[0002] 1. The Field of the Invention

[0003] This invention relates to tube couplings which may be single ormultiple tube couplings providing inline, elbow or T-couplings or tubeclosures.

[0004] 2. The Relevant Technology

[0005] Our “Speedfit” tube connector (the subject of UK Patent No.1520742) has a coupling body with a throughway open at one end and atapered cam surface in the open end to receive a collet for locking atube in the coupling. The collet is compressed against the tube by aslight withdrawal of the tube and collet from the coupling body whichlocks the tube in the coupling body. The collet can be depressed intothe body to release the tube.

[0006] Our “Superseal” connector (the subject of our UK Patent No.2167147) has a separate sleeve screwed onto the open end of the couplingbody in which the tapered cam is formed. By screwing the sleeve onto thecoupling body the gripping action of the collet on the tube isincreased. Also the collet becomes locked up in the coupling body andcannot be depressed to release the tube.

[0007] Our “Speedfit/Superseal” coupling (the subject of European PatentPublication No. 0945662) comprises a coupling body having a throughwayopen at one end to receive an end portion of a tube and having aninternal cam surface tapering towards the open end in which a collet islocated for locking the tube in the coupling body by engagement with thetapered cam surface, and having step means to limit entry of the colletinto the throughway, the coupling body having a main body the throughwayof which receives the end of a tube and contains said step means tolimit insertion of the collet and an end cap in screw threadedengagement with the main body containing said open end to the throughwayand the tapered cam surface, and indexing means between the end cap andmain body to define different positions of rotational adjustment in thefirst of which a tube can be inserted and, by depressing the collet intothe coupling body, released from the coupling body and in the second ofwhich the collet is engaged with the step means to prevent the colletbeing depressed into the coupling body to release the tube. In thepreferred arrangement the end cap has an internally threaded sleeveportion encircling and in screw threaded engagement with an externalthread on the main body.

[0008] In the latter construction, an “O” ring seal is provided in thethroughway in the coupling body to engage and seal with the outersurface of the tube. The seal is spaced from the ends of the collet by awasher or sleeve. This arrangement provides small cavities betweenadjacent components in which liquids can penetrate and become trappedand difficult to remove by cleaning. Such entrapped liquids candeteriorate over a period of time and cause contamination in subsequentliquid flowing through the coupling.

[0009] Our European Patent Publication No. 1233225 discloses a tubecoupling to receive and hold a tube comprising a coupling body having athroughway open at one end to receive a tube, an annular step in thethroughway facing the open end to receive an end of a tube, an end capengaging the coupling body for axial movement between forward andretracted position on the coupling body, the end cap having an openingfor the tube to extended through, a seal located in the coupling bodybetween the step and the open end of the body and in the form of anannular sleeve encircling the throughway, the seal having an out turnedannular flange at one end which engages with the annular step to receiveand seal with an end of the tube inserted into the throughway and meansoperable by the end cap to compress the sleeve around the outer surfaceof the tube adjacent said end of the tube to from a seal with the end ofthe tube.

[0010] This arrangement provides a combination of the “Speedfit” and“Superseal” features referred to above in which any potential leak pathsfrom an end of a tube in the coupling body is minimised and recesses orcavities between adjacent components in the leak path are minimised topresent a substantially clean, smooth internal surface to the outer sideof the tube connected in the coupling.

[0011] The latter arrangement is, however, relatively complicatedrequiring inter fitting components which present some manufacturingdifficulties particularly for small sizes of tube couplings.

SUMMARY OF THE INVENTION

[0012] This invention provides a tube coupling to receive and hold atube comprising a coupling body having a throughway open at one end toreceive an end portion of tube, an annular step in the throughway facingthe open end to provide an end stop for a tube end, an end cap engagingthe coupling body for axial movement between forward and retractedpositions on the body, the end cap having an opening for the end portionof the tube to extend therethrough and a tube locking device in the capto promote entry of a tube into the cap and to resist withdrawal of thecap, an annular seal located in the coupling body adjacent the annularstep, the seal having an inner annular portion with which the tube endis engageable and an outer annular portion, and means to compress theouter annular portion of the seal axially in response to forwardmovement of the end cap to cause the inner portion of the seal to bepressed into sealing engagement with the tube end.

[0013] For example, the means to compress the outer portion of theannular seal may comprise an annular sleeve located in the throughway inthe coupling body through which the tube extends, the sleeve having oneend in engagement with the outer annular portion of the seal and theother end in engagement directly or indirectly with the cap to be forcedinto engagement with the seal by forward movement of the cap on thecoupling body.

[0014] The annular seal may be in the form of an annular disc having aninner and an annular portion for engagement by the tube end, and anouter annular portion for engagement by said compressing means.

[0015] More specifically, the outer portion of the annular seal may havean annular projection facing the open end of the coupling body withwhich said compressing means is engageable, the end portion of the tubeengaging the inner annular portion of the seal within the projection sothat compression of the projection presses the projection into sealingengagement with the outer surface of the tube.

[0016] The projection on the outer annular portion of the seal maycomprise a shallow collar formed on the outer periphery of the sealwithin which the tube end may engage, the collar having a rounded endportion with which the means to compress the outer portion of the sealengage.

[0017] Alternatively, the outer annular portion of the seal may have atoroidal shape project within which the end portion of the tube engagesthe seal and with which the means to compress the outer portion of theseal engage the toroidal shaped projection when compressed the sealingagainst the outer surface of the tube end.

[0018] In any of the above arrangements the tube locking device in thecap may comprise an annular collet having a plurality of resilient armsand the cap has a cam surface which tapers towards the open end of thecap with which the resilient arms of the collet are engageable to bepressed inwardly with movement of the collet towards the open end of thecap to force the arms into gripping engagement with the tube.

[0019] In the latter arrangement, the ends of the arms of the collet maybe engageable with the means to compress the outer portion of thesealing ring so that when the cap is moved in a forward direction on thecoupling body, the collet moving with the cap forcing the compressionmeans to act on the outer portion of the seal to compress the seal intosealing engagement with the end of the tube.

[0020] Also in any of the above arrangements the interengaging means maybe provided between the cap and coupling body which, on rotation of thecap in one direction drives the cap forwardly on the coupling body andin the opposite direction rearwardly on the coupling body.

[0021] By way of example, the coupling body may have a spirally woundgroove, and the cap has a projection or projections engaging in thegroove to cause the cap to move forwardly or rearwardly on the body withrotation of the cap in one or other direction.

[0022] More specifically, the spirally wound groove on the coupling bodymay extend approximately half way round the coupling body and the capmay have a projection engaging in the groove so that a half turn of thecap with respect to the coupling body advances or retracts the cap overthe total travel of the cap permitted by the groove.

[0023] In the latter arrangement detent means may be provided forretaining the projection in the fully advanced or fully retardedposition in the helically wound groove.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The following is a description of some specific embodiments tothe invention, reference being made to the accompanying drawings inwhich:-

[0025]FIG. 1 is an exploded perspective view of a straight double-endedconnector for two lengths of tube;

[0026]FIG. 2 is a sectional view through the coupling of FIG. 1;

[0027]FIG. 3 is a sectional view through a first modified version of thecoupling of FIG. 1; and

[0028]FIG. 4 is a sectional view through a second modified version ofthe coupling

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Referring firstly to FIGS. 1 and 2 of the drawings, there isshown a tube coupling which is generally of the form described andillustrated in our European Patent Publication No. 0945662. Thatapplication discloses a tube coupling embodying features of our“Speedfit” tube connector which forms the subject of our UK Patent No.1520742 with the features of our “Superseal” connector as described inour UK patent No.2167147. The tube coupling comprises a coupling bodyhaving a main body part end cap on the body part, and a collet forgripping a tube to be locked in the coupling body located in the end capwith a seal for engaging the tube is located in the main body part. Inone position of the end cap on the main body part, a tube can be lockedin or released from the coupling body by the collet as described in ourUK Patent Publication No. 1520742. The gripping action of the collet onthe tube can enhanced by screwing the end cap further onto the main bodypart of the coupling as described in our UK Patent PublicationNo.2167147 and means are provided as described in our European PatentPublication No. 0945662 to index the movement of the end cap withrespect to the main body part so that the end cap is readily adjustablebetween the first position in which the tube can be engaged by a colletbut readily released when required and a second position in which thetube is locked against release in the collet.

[0030] In accordance with the present invention, a tube connectorcomprises a coupling body 10 having a throughway 11 open at one end 12to receive internally an end portion of a tube (not shown) andexternally an end cap 13. The coupling body has a pair of helicalgrooves 14 spaced diametrically apart around the body, each having anaxially extending entry 15 over a step 16. The grooves extend from theentry around and along the coupling body to terminate at inner ends 17adjacent an enlarged integral collar 18 encircling the coupling body.The caps 13 has lugs 19 spaced diametrically across the lugs 14 on theinner periphery of the cap to engage in the grooves 14. The cap 13 ispresented to the coupling body with the lugs 19 in line with the entryends 15 to the grooves. The lugs are snapped over the steps 16 by anaxial movement of the cap following which the cap can be tightened ontothe coupling body by rotation. As the cap rotates the lugs 18 traversethe grooves 14 drawing the cap along the body until the lugs reach theinner ends 17 of the grooves adjacent the central block 11 a.

[0031] The end cap 13 has an open end 20 in which a collet indicatedgenerally at 21 is engaged. The collet comprises an annular portion 22which projects from the open end 20 of the end cap and is formed with anout turned annular flange or head 23 which can be manually gripped formanipulating the collet. A portion of the collet extending into thethroughway in the end cap has axially extending resilient arms 24 withwhich terminate in heads 25 having integral barbs or teeth 26 on theinner sides thereof to grip the tube extending through the collet.

[0032] There is a tapered cam surface 27 formed in the end cap withwhich the heads 25 of the collet are engageable to be compressedinwardly as the collet is drawn outwardly of the throughway to cause thebarbs 26 on the inner sides of the heads of the collet to grip andengage a tube extending through the collet.

[0033] The throughway 11 in the main body part is formed with a step 28facing the open end of the coupling body to receive an end of a tube tobe connected in the coupling body. An annular seal 29 is positioned inthe coupling body against the annular step 28. The seal has an innerannular portion 30 to receive an end of a tube to be secured in thecoupling body as described later. The end of the tube is cut square toensure full engagement with the seal. The seal has an outer annularportion 31 and an annular sleeve 32 is slidably located in thethroughway between the outer portion 31 of the seal and the heads 25 ofthe collet.

[0034] As shown in FIG. 2 of the drawings the end cap 13 is in itsretracted position in which a tube is received. The tube is pushed fullyhome into the coupling body by turning the end cap 13 throughapproximately a halfturn of movement with the tube locked in the cap bythe collet. The endcap advances along the coupling body and the end oftube is moved in engagement with the seal 31. The heads 25 of the endsof the arms 14 of the collet engage the adjacent end of the sleeve 32forcing the sleeve further into the coupling body. The sleeve 32 isforced by the collet against the outer portion 31 of the seal tocompress the seal and force the inner portion 30 into engagement withthe end of the tube.

[0035] One end only of the coupling body has been described and theother end of the body illustrated which is an in-line connector issimilarly formed.

[0036]FIG. 3 of the drawings shows a further arrangement in which theseal 29 is formed with an axially projecting collar 33 around the outerperipheral portion 31. The collar has a rounded end 34 with which thesleeve is engageable. The end of the tube engages the seal within thecollar and pressure of the sleeve on the collar forces the collarinwardly to seal with the outer periphery of the tube in addition to theend seal on the tube.

[0037]FIG. 4 shows a still further arrangement in which the seal 29 hasa raised toroidal shaped projection 35 around the outer portion of theseal with which the sleeve is engageable to press the toroid shapedprojection in engagement with the periphery of the tube. Other featuresof the arrangement are as previously described with reference to FIGS. 1and 2.

What is claimed is:
 1. A tube coupling to receive and hold a tubecomprises: a coupling body having a throughway open at one end toreceive an end portion of a tube; an annular step in the throughwayfacing the open end to provide an end stop for a tube end; an end capengaging the coupling body for axial movement between forward andretracted positions on the body, the end cap having an opening for theend portion of the tube to extend therethrough and a tube locking devicein the cap to promote entry of a tube into the cap and to resistwithdrawal of the cap; an annular seal located in the coupling bodyadjacent the annular step, the seal having an inner annular portion withwhich the tube end is engageable and an outer annular portion; and meansfor compressing the outer annular portion of the seal axially inresponse to forward movement of the end cap to cause the inner portionof the seal to be pressed into sealing engagement with the tube end. 2.A tube coupling as claimed in claim 1, wherein the means for compressingthe outer portion of the annular seal comprises an annular sleevelocated in the throughway in the coupling body through which the tubeextends, the sleeve having one end in engagement with the outer annularportion of the seal and the other end in engagement directly orindirectly with the cap to be forced into engagement with the seal byforward movement of the cap on the coupling body.
 3. A tube coupling asclaimed in claim 1, wherein the annular seal is in the form of anannular disc having an inner and an annular portion for engagement bythe tube end, and an outer annular portion for engagement by the meansfor compressing.
 4. A tube coupling as claimed in claim 2, wherein theannular seal is in the form of an annular disc having an inner and anannular portion for engagement by the tube end, and an outer annularportion for engagement by the means for compressing.
 5. A tube couplingas claimed in claim 1, wherein the outer portion of the annular seal hasan annular projection facing the open end of the coupling body withwhich the means for compressing is engageable, the end portion of thetube engaging the inner annular portion of the seal within theprojection so that compression of the projection presses the projectioninto sealing engagement with the outer surface of the tube.
 6. A tubecoupling as claimed in claim 2, wherein the outer portion of the annularseal has an annular projection facing the open end of the coupling bodywith which the means for compressing is engageable, the end portion ofthe tube engaging the inner annular portion of the seal within theprojection so that compression of the projection presses the projectioninto sealing engagement with the outer surface of the tube.
 7. A tubecoupling as claimed in claim 5, wherein the projection on the outerannular portion of the seal comprises a shallow collar formed on theouter periphery of the seal within which the tube end may engage, thecollar having a rounded end portion with which the means for compressingthe outer portion of the seal engage.
 8. A tube coupling as claimed inclaim 5, wherein the outer annular portion of the seal has a toroidalshape project within which the end portion of the tube engages the sealand with which the means for compressing the outer portion of the sealengage the toroidal shaped projection when compressed the sealingagainst the outer surface of the tube end.
 9. A tube coupling as claimedin 1, wherein the tube locking device in the cap comprises an annularcollet having a plurality of resilient arms and the cap has a camsurface which tapers towards the open end of the cap with which theresilient arms of the collet are engageable to be pressed inwardly withmovement of the collet towards the open end of the cap to force the armsinto gripping engagement with the tube.
 10. The tube coupling as claimedin claim 9, wherein the ends of the arms of the collet are engageablewith the means for compressing the outer portion of the sealing ring sothat when the cap is moved in a forward direction on the coupling body,the collet moving with the cap forcing the means for compressing to acton the outer portion of the seal to compress the seal into sealingengagement with the end of the tube.
 11. A tube coupling as claimed in1, further comprising means for interengaging the cap and the couplingbody such that rotation of the cap in one direction drives the capforwardly on the coupling body and in the opposite direction rearwardlyon the coupling body.
 12. A tube coupling as claimed in claim 1 1,wherein the means for interengaging comprises the coupling body having aspirally wound groove, and the cap having a projection or projectionsengaging in the groove to cause the cap to move forwardly or rearwardlyon the body with rotation of the cap in one or other direction.
 13. Atube coupling as claimed in claim 12, wherein the spirally wound grooveon the coupling body extends approximately halfway round the couplingbody and the cap has a projection engaging in the groove so that a halfturn of the cap with respect to the coupling body advances or retractsthe cap over the total travel of the cap permitted by the groove.
 14. Atube coupling as claimed in claim 12, further comprising means forretaining the projection in the fully advanced or fully retardedposition in the helically wound groove.
 15. A tube coupling as claimedin claim 13, further comprising means for retaining the projection inthe fully advanced or fully retarded position in the helically woundgroove.